S-1 and Oxaliplatin (SOX) Plus Sintilimab in the Locally Advanced Esophagogastric Junction Adenocarcinoma

Inclusion Criteria:

1. Written (signed) informed consent;
2. Histologically CT/MRI confirmed cT3-4aN+M0 Esophagogastric Junction Adenocarcinoma;
3. Consent to send tumor tissue from biopsy or resection for PD-L1, EBV, MSI detection;
4. Female or male, 18-75 years;
5. ECOG 0-1, no surgery contraindications;
6. Physical condition and adequate organ function to ensure the success of abdominaland/or thoracic surgery;
7. Expected survival ≥ 6 months;
8. Adequate hematological, liver, renal and coagulation function; 1) Platelet (PLT) count ≥100,000 /mm3; 2) White Blood cell（WBC）count ≥4,000 /mm3 and ≤15,000 /mm3 ；Neutrophilcount (ANC) ≥1,500 /mm3; 3) Hemoglobin (Hb) level ≥9.0 g/dl; 4) Internationalnormalized ratio (INR) ≤1.5; 5) Prothrombin time (PT) and activated partialthromboplastin time (APTT) ≤1.5×ULN; 6) Glycosylated hemoglobin (HbA1c) <7.5%; 7)Total bilirubin (TBIL) level ≤1.5×ULN; 8) Alanine aminotransferase (ALT) and aspartateaminotransferase (AST) level ≤2.5×ULN (≤5×ULN in case of liver metastasis); 9)Alkaline phosphatase level ≤2.5×ULN (≤5×ULN in case of liver metastasis); 10) Serumcreatinine (Cr) level ≤1.5×ULN and creatinine clearance ≥60 ml/min;
9. Patients with Good compliance, who can cooperate with the laboratory, auxiliaryexaminations and corresponding specimen collection of this program set;
10. Females of child bearing age must have a negative pregnancy test, and have to takecontraception measures and avoid breast feeding during the study and for 6 monthsafter the last dose; male subjects must agree to taken contraception measures duringthe study and for 6 months after the last dose.

Exclusion Criteria:

1. Suffer from other active malignant tumors within 5 years or at the same time. Curedlocalized tumors, such as skin basal cell carcinoma, skin squamous cell carcinoma,superficial bladder cancer, prostate carcinoma in situ, cervical carcinoma in situ,breast carcinoma in situ, etc. can be included in the group.
2. Patients who are planning to undergo or have previously received organ or bone marrowtransplantation.
3. Myocardial infarction or poorly controlled arrhythmia (including QTc interval ≥ 450 msfor males and ≥ 470 ms for females) occurred within 6 months before the firstmedication (QTc interval is calculated by Fridericia's formula).
4. There is NYHA standard grade III to IV cardiac insufficiency or color Dopplerultrasound examination: LVEF (left ventricular ejection fraction) <50%.
5. Human immunodeficiency virus (HIV) infection.
6. Suffer from active tuberculosis.
7. Past and present patients who have interstitial pneumonia, pneumoconiosis, radiationpneumonia, drug-related pneumonia, severely impaired lung function, etc., which mayinterfere with the detection and management of suspected drug-related lung toxicity.
8. There is a known active or suspicious autoimmune disease. Except those who were in astable state of the disease at the time of enrollment (no need for systemicimmunosuppressive therapy).
9. Received treatment with live vaccine within 28 days before the first administration;except for the treatment of seasonal influenza with inactivated viral vaccine.
10. Patients who need to receive systemic corticosteroids (> 10 mg/day curative dose ofprednisone) or other immunosuppressive drugs within 14 days before the firstmedication or during the study period. However, the following conditions are allowedto enter the group: in the absence of active autoimmune diseases, patients are allowedto use topical or inhaled steroids, or adrenal hormone replacement therapy with a doseof ≤ 10 mg/day prednisone.
11. Any active infection that requires systemic anti-infective treatment occurs within 14days before the first administration of the drug; except for receiving preventiveantibiotic treatment (such as prevention of urinary tract infection or chronicobstructive pulmonary disease).
12. Have received other antibody/drug treatments for immune checkpoints in the past, suchas PD-1, PD-L1, CTLA4 and other treatments.
13. Are receiving other clinical research treatments, or the planned start of thisresearch treatment is less than 14 days from the end of the previous clinical researchtreatment.
14. Known to have a history of severe allergies to any monoclonal antibodies or study drugexcipients.
15. Known history of psychotropic drug abuse or drug use; patients who have stoppeddrinking can be included in the group.
16. There are patients who may increase the risk of participating in research and researchmedication, or other severe, acute and chronic diseases, who are not suitable forparticipating in clinical research based on the judgment of the investigator.